Tiny kitchen, 3 utilities on 1 tile?

Well, you can already get at least one combination of two of those three items onto a single tile in-game -- there are cooktops that will go on a countertop and mini-fridges that will go inside a counter. (There may even be a minifridge and cooktop where you can just put the cooktop on top of the minifridge without using a counter, but I'd have to load the game to check on that.) Around the Sims in particular has content for that.

There are also mini-sinks designed to fit onto a toilet, and since I think there's a least one cooktop that doesn't take up the entire surface of one tile's worth of counter, it might be possible to combine a half-counter cooktop with a (newly made for this purpose, the toilet ones are probably not set up right) half-counter sink, but knowing whether they'll really all play nicely together in a few different ways is above my pay grade. I'm curious enough now to consider trying it with things already in my game, though.

Getting all the code onto one object is another issue I can't speak to, but again there are single objects that merge the tuning of two existing game objects into one... the question of how the animations will look is potentially an issue with both single object and multiple object combos, of course.